New research, however, may dash some of this enthusiasm for people with COPD, an umbrella name for chronic lung diseases, including chronic bronchitis and emphysema. People with COPD often experience a worsening of their breathlessness and other symptoms (exacerbations) throughout the course of their disease.

But vitamin D doesn’t seem to reduce the number of these exacerbations. That said, vitamin D did benefit a small group of 30 people in the study who had severely low vitamin D levels when the study began.

The new findings appear in the Annals of Internal Medicine.

Low Vitamin D Levels and COPD

Vitamin D is often referred to as the sunshine vitamin because our bodies produce it when exposed to sunlight. The Institute of Medicine recommends that people aged 1 to 70 take in 600 international units (IUs) of vitamin D per day, and people older than 70 should aim for 800 IUs. Some foods like fish and fortified dairy and juice products are rich in vitamin D, but supplements are also used to raise blood levels.

The new study included 182 people with COPD. Participants orally received 100,000 IU of vitamin D or an inactive placebo monthly for a year. There were 468 exacerbations during the study period, and there was no difference in the numbers between the different groups. There were also no differences in time to the first exacerbation between those who received vitamin D and those who did not.

People who took vitamin D did not report greater improvements in their quality of life or the number of times they were hospitalized for COPD, the study shows. Vitamin D also had no bearing on their lung function and risk of death.

However, in looking at a small subset of people with severely low vitamin D, the rate of exacerbations decreased among people who received vitamin D, the study showed. But the researchers note that the number of people in their study with severely low vitamin D was very small, so future studies to look at a possible benefit from vitamin D in people with severely low vitamin D levels need to be done to support the findings.

Screen for Low Vitamin D in COPD

Screening people with COPD for low vitamin D makes sense, says researcher Wim Janssens, MD, PhD, of the University Hospitals Leuven in Leuven, Belgium. “Be aware that vitamin D deficiency is prevalent in COPD and that it needs supplementation for bone health reasons,” he says in an email. Vitamin D helps the body absorb calcium, which is important for bone health.

“Severe deficiency of vitamin D levels ... may even increase the COPD exacerbation rate and needs therefore aggressive supplementation,” he says. But “don’t think that supplementation will cure your disease.”

Barry Make, MD, agrees. He is a pulmonologist at National Jewish Health in Denver. “The study suggests that going forward maybe we should study preventing exacerbations in people that have low vitamin D levels,” he says.

His bottom line? “Vitamin D is important to measure and if it is low, it makes sense to supplement,” he says.

Adam Wanner, MD, is a pulmonologist at the University of Miami Miller School of Medicine. He says the jury is still out on what role vitamin D supplements have, and in which COPD patients. “There were no benefits in terms of exacerbations in the study, but when they looked at the subset of those who had severe vitamin D deficiency, there was a benefit,” he says. “This is an important study in the sense that it helps us design future studies.”

The results of the study are in the eye of the beholder, says Michael Holick, MD, PhD. He is the director of the Vitamin D, Skin, and Bone Research Lab at Boston University. Holick has been championing vitamin D for years.

“Vitamin D has benefit above and beyond bone health,” he says. “There was a significant benefit for those people in the study who were most deficient.”